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(No Model.) GSheets-Sheet 1.

W. M. SOHLESINGER.

ELECTRIC ROCK DRILL.

No. 449,090. Patented Mar. 24,1891.

WITNESSES: JNVE/VTOR/ gumxmww 7C3 WW7?! SW70,

A TTORNE V (.No Model.) 6 Sheets-Sheet 2.

W. M. SOHLESINGER.

ELECTRIC ROCK DRILL.

No. 449,090. Patented Mar. 24, 1891.

W! TNESSES: [NVEN TOR/ mmnosmufi zwym'wfl' A TTORNE V v m; m, mare-LIT(No Model.) 6 Sheets-Sheet 3. W. M. SOHLESINGER.

ELECTRIC ROCK DRILL.

No. 449,090. Patented Mar. 24, 1891.

WITNESSES: r [NI EN T OR Qmwwoflwb fmz m a. JM

ATTORNEY m5 Norms pnzns cm, wow-mun. msmm-rcu, o. c

(No Model.) 6 Sheets-Sheet 4. W. M. SGHLESINGER.

ELECTRIC ROCK DRILL.

No. 449,090. PatentedMar. 24, 1891.

[NVENTOR W ATTORNEY WITNESSES. WW

(No Model.) 6 Sheets-Sh6et 5.

- W. M. SGHLESINGER.

ELEG'IRIG ROCK DRILL.

N0. 449,090. Patented Mar. 24, 1891.

INVENTOR/ mm 046 SW allllllllllllilllllll'l ATTORNEY (No Model.) 6Sheets-Sheet 6. W. M. SOHLESINGER. ELECTRIC ROCK DRILL.

No. 449,090. Patented Mar.'24,1891.

WITNESSES: INVENTOR,

A TTOR/VE V UNITED STATES PATENT OFFICE.

\VI'LLIAM ML SCIILESINGER, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TOGIIARLFS F. VAN HORN, OF SAME PLACE.

ELECTRIC ROCK DRlLL.

SPECIFICATION forming part of Letters Patent No. 449,090, dated March24, 1891. Application filed November 17, 1888. Serial No. 291,140. (Nomodel.)

To all whom it may concern.-

Be it known that I, \VILLIAM ll. SCHLES- INGER, a subject of the Queenof Great Britain, residing at Philadelphia, in the county ofPhiladelphia and State of Pennsylvania,

have invented certain new and useful Improvements in ElectricRock-Drills, of which the following is a specification.

My invention has relation to power rotary io rock-drills in general, andparticularly to portable rock-drills; and it has for its object to soconstruct the drill that it can be electrically operated, to provide aneconomical form of construction of e1eotrically-rotated rock-drill I 5which is exceedingly durable and efficient, and to provide a simple anddurable drill-rod feed-regulator of the form which, when predeterminedlyadjusted automatically, acts to vary the degree of feed for the drill oranger to correspond with or suit the varying hardness of materialthrough which the anger is working or penetrating, so as to avoiddamaging or injurying the anger as it suddenly passes from a soft to ahard substance, and,

furthermore, to enable one and the same feed mechanism and drill-rod tobe used for working in materials of varying hardness.

My invention accordingly consists of the combinations, constructions,and arrange- 3o ments of parts, as hereinafter described in thespecification, and pointed out in the claims, reference being had to theaccompanying drawings, wherein- Figure 1 is a longitudinal section of aportable rotary rock-drill embodying my im pro vements, thesupporting-coluinn therefor not being shown. Fig. 2 is a horizontalsection of part of same, showing more plainly the horns or lugsprojecting from the ends of the motor field-magnet poles and connectionbetween the same and the ends of the casing therefor. Fig. 3 is an endview, partly sectional, on the line 11 11, Fig. 1, showing partof thesupporting-column and connection between the column and drill-casing.Fig. 4 is a like view,

partly sectional, on line 2 2 2", Fig. 1, the supporting-column notbeing shown. Fig. 5 is an elevation of the feed-nut for the drillrod.Fig. 6 is an end view of same. Fig. 7 is an inverted plan of thedrilland supporting-column, the latter being in section. Fig.

8 is an elevation of preferable form of holders for the brushes for thecommutator for the electric motor. Fig. 0 is a plan of same. Fig. 10 isa sectional elevation, partly broken away, of the supporting-column forthe drill. Fig. 11 is a section, partly in plan, through the hand-wheelon the supporting-column. Fig. 12 is a section drawn to an enlargedscale on the line 2 2", Fig. 1. Fig. 13 is an elevation of the handle orturning end of electric switch for the motor and resistance-box withspring-pawl and ratchet-locking mechanism therefor. Fig. 1% is adiagrammatic plan showing more plainly the circuit-connections betweenthe switch, resistances, and electric motor. Fig. 15 is a sectionalelevation of part of the motor-armature shaft and feed-rod, showing amodified form of feed mechanism for the drill-rod; and Fig. 1c is adetail ele- 7o vation of part of the same, partly in section.

A represents a casing or box, composed of, preferably, a base-plate a,ends a a and a sheet-metal cap or cover a forming the top and sides ofcasing. The ends a a are preferably screwed to the base-plate, asindicated at o or they may otherwise be fastened to the plate, asdesired.

On the under side of the base-plate a, near its front end, is a tubularbearing I3, in which is journaled a tubular sleeve 1, having in its borekeys K), at one end a collar Z1 fitting or engaging with a slot 1/ inthe base-plate a, and at its other end a gear-wheel Z)", which wheel andsleeve, if desired, may be integral, as shown. Through the sleeve Z)passes the drill-rod C, (indicated in dottedlines, Fig. 1,) which haslongitudinally-arranged peripheral key-slots c for engagement with thekeys Z) in the bore of sleeve Z) to provide for rota- 0 tion of thedrill or feed rod with the sleeve Z), and at the same time admit of thedrill-rod sliding or feeding longitudinally through the sleeve whenactuated by the feed mechanism.

The latter consists of a two-part cylindrical 5 or tubular nut D, smoothon its exterior surface, interiorly threaded at (Z, and having betweenits parting edges springs d, which tend to normally spread the sectionsof the nut D apart. The nut D is loosely supported between two slidingdogs or jaws E E, curved to conform to the nut and having end flanges eoverlapping the ends of the nut to prevent endwise movement of thenut-sections when they are out of contact or engagement with thedrill-rod C. The dogs or jaws E have at their upper extremities ends orfeet e',-which fit and slide in transverse ways-or guides e in thebed-plate a. The feet e have threaded openings e ,the threads in onebeing right and the other left handed, which respectively engage withright and left screw-threads on adjusting-rod e, which may be mountedupon the bed-plate a, as shown more plainly in Fig. 12, or otherwiseswiveled on the bedplate, as desired, in order that when the rod isturned it will not have a lengthwise movement, so that by turning rod ein one direction the jaws E E approach each other until they contactwith the sections of nut D, and close them together until their partingedges meet, to effect engagement between the nut and drill-rod, and,further, to produce a frictional clamping between the nut and the jaws,and by more or less reversely turning said rod 6 the clamping orfrictional pressure between the jaws and nut is decreased, or the jaws EE are drawnapart to admit of the springs 01' spreading the nut-sectionsapart to totally release the engagement between the drill-rod and thenut to enable the drill-rod to be manually pulled backward or forwardrapidly for adjustment or exchanging of angers. As the parting edges ofthe nut-sections meet when the sections are closed into engagement withthe drill-rod, the pressure of the jaws on the nut-sections impart nopressure of the nut-sections on the drill-rod. Consequently the fullpower exerted by the motor is employed for drilling and not forovercoming useless frictional contact between the nut and drill-rod.

Secured to or formed on the top of the baseplate a are the cores andpole-pieces for the field-magnets f of a form of electric motor F,having a rotating armature G and armatureshaft g, and to admit of morereadilyv winding the helices f on the field-magnets I prefer tolongitudinally divide the base-plate, as indicated at 00, Fig. 7, inwhich case the tubu lar bearing 13 is also correspondingly divided andthe bed-plate sections are connected by transverse bolts a and thesleeve-sections B by a yoke or bar b The motor-armature G may be of anysuitable construction, and its shaft g is mounted in bearings g, securedto or formed on the casing ends a a One end of said armature-shaftprojects beyond end a of the casing, and upon it is mounted a pinion 9which gears with wheel b for transmitting power to the sleeve 17 and inturn to the drill-rod for rotating it. From the ends of the pole-piecesof the field-magnets f project horns or lugs f (see more plainly Fig.2,) the outer ends of which have a screw or bolt connection f with theends of the casing to stiffen and strengthen the same against the sidethrust of the motor. The lugs at the commutator end of thearmature-shaft, which commutator is shown at f, form supports for thebrush-holders H.

Any suitable form of brush -holder and brushes may be used. In thedrawings, Figs. 8 and 9, I have shown a preferable form of same, whereinthe holder H is secured to but insulated from the lugs f and consists,essentially, of a frame or bracket h, having at its forward end atransverse slot h, preferably opened at one'end to admit of easyreplacement of brushes and secure compactness of parts. Said slot isclosed at its open end by a screw b to keep the brushes in position.Through slot 71' vertically passes the brush h the thickness of which isless than that of the slot, so that. the brush will have lateral play inthe slot to assume a slightlyinclined vertical position for contact withthe commutator-segments, being maintained in such contact by means of apresser-bar 72, bearing upon the outer end of the brush. The

be connected to a spiral or other spring h by a set-screw mechanism h sothat the degree of pressure upon the brushes to maintain their contactwith the commutator may be regulated as desired. The vertical positionof the brushes is due to the location of the neutral line of the motoras it is constructed, and in this position they are easy of access forreplacement or adjustment through openings h in the casing end a whichare covered by doors or slides h The brushes are inclined, so as to givea softer contact with and have a more even pressure on the commutator.The slot h is made wider than the width of the brush to enable the brushto take up oppositely-inclined positions in case of reversal from theoutside.

The. sheet-metal casing-cap a is preferably made of brass or othernon-magnetic materesser-bar h ma beas rin -bar or it ma IIO rial for thepurpose of preventing short circuiting of the magnet-circuit, and withinthe casing, near the top of the same, and secured to said cap, is aresistance-box L, having circuit-connections with a suitable electriccontrolling-switch K for the motor. The movable part K of said switch,the resistancebox L, the contact-fingers between the switch andresistance-box, and the line-wire bindingposts or couplings are allmounted on or secured to cap a while the contact-fingers between theswitch and motor are secured to the end a of the casing, so that thecasingcap a canbe removed and replaced without necessitating dismantlingany of said parts. The binding-posts for the line-wire 1 l are shown inthe form of a coupling-section N, as described and claimed in a pendingapplication filed by me on the 2d day of October, 1888, Serial No.286,979, so that the ends of the line-wire secured to a matecoupling-section can easily and safely be connected to and disconnectedfrom coupling-section N.

The switch K, as shown in the drawings,

consists of a rotating cylinder K, of insulating material, suitablymounted in hearings in the sides of cap a having an outside knob orturning-handle 7;. (See more plainly Figs. 3, at, '7, and 14.) Upon saidcylinder are oppositely-located segmental contact-plates 7t" 7t,electrically connected, as indicated at 7t", and 7c" 7r? are therespective contact-fingers therefor. (See more plainly Fig. ll.) k isanother segmental contact-plate, having steps 7.1 it 76, which is inelectrical contact, as indicated at with a segmental contact-plate 7t onsaid cylinder in line with the step it of plate 7;.

7& is the contact-finger for contact-plate 7t, and 113 7.1 and 7.9 arethe respective contactfingers for the steps 71: 7f, and it of plate 7;.One side of the line-circuit lends to contactfinger 7& and the otherside of said line is connected to contaet-finger 7.1 and the latter andthe fingers 7t 7.; are in circuit with the resistance-box L. Theelectric motor F is in circuit with the contact-fingers 71;" 7. \Vhenthe cylinder K is in the position shown in Fig. let, the circuit fromthe line 1 1 to the motor is by way of contact-finger 73 through theresistance-box L and finger 7; to contactfinger 7e, and all theresistances in said box are included in the circuit, thence by wayofplate 705 or its step 75 and connection 7.1 to plate 7;, and thence byway of finger 73 to and through the motor to finger 7e" and plate 7t,and finally by connection 7r to plate 7; and finger 7; to the other sideof the line. This described position of the switch is the one in whichthe motor is started and all the resistances L are included in thecircuit to enable the motor to be started slowly and the work adjustedbefore drilling full speed.

turning the cylinder or switch part K in the direction of the arrow,Fig. 14., until the finger 7d contacts with step b of plate 7t part ofthe resistance in box L is cut out, and a further turning of saidcylinder until the finger 75 contacts with the plate-step it cuts theresistance L out of circuit and the motor is then doing its maximumwork. By reversely turning said cylinder the resistances are included inthe circuit, and when the cylinder is turned until all the fingers passoff of the contact-plates the motor is cut out of the line-circuit. Ifdesired, a suitable reactingspringt (see Fig. 1) may be used for reversely turning cylinder K. To maintain the cylinder K in the positionto which it is adjusted, a collar Z is secured to its sliaftl outside ofthe casing, (see more plainly Fig. 13,) which collar has a number ofperipheral notches Z corresponding to the number of fixed positionsdesired for the cylinder, and these as the cylinder is turned come intosuccessive engagement with a spring-pawl Z to lock the cylinder in itsadjusted position.

Adjacent to one side of the bed-plate a and to its under side, orotherwise suitably located, is formed a socket m, into which screws abolt m, swiveled in sleeve or ring M on a column or support P. Thesleeve M rests upon a collar 0, secured to column Pbya setscrew 0, sothat the drill, sleeve M, and collar 0 can be adjusted vertically onsaid column. The sleeve M is parted or split at m and has aclamping-screw in thereat, so that by loosing said screw on the drillmay be rotated horizontally to any desired position, and by tighteningsaid screw on" the sleeve M is clampedto the column to secure the drillin its adjusted position. The bed-plate socket m is secured to the screwm, swiveled to sleeve M to admit of placing the drill-rod in a vertical,horizontal, or angular positionfor work or drilling.

Any suitable form of vertical or horizontal or other column P may beused. In the drawings I have shown a form of vertical column comprisinga two-prong or other numbered prong-base p, to which is jointed a plug11, secured in the bottom end of a tube 12 which has at its upper end atubular plugp the bore of which is threaded to receive a screw 1),having a hand-wheel p and a swiveled pointed top p. By manipulatinghand-wheel p the length of the column may be increased, as desired, andthe prongs onthe base 1) prevent twisting or rotation of the column Pwhen the drill is in operation.

hen the drill is in proper position for working, the coupling-connectionat the end of the line-wire is connected to coupling-section N on thecasing A, and the screw-rod c" is turned to move jaws E E to cause thesections of nut D to come together and engage with the drill-rod, andalso to produce between the jaws E and said nut the frictional pressuredesired therefor, which pressure in practice depends upon the strengthof the drill and the power of the motor thereon. The switch K beingmanipulated to the position shown in Fig. ll, the drill-rod is slowlyrotated and as there is no baclepressure on the drill-rod, or, in otherwords, as there is no pressure between the nut and drill-rod opposing orovercoming that between the nut and jaws E, the nut remains stationaryand feeds the drill-rod forwardly at full speed to bring the auger up tothe work. As soon as the auger meets the material and begins to drill orto work therein, the back-pressu re, due to the resistance which theauger meets with on penetrating the materials, falls on the nut D. Ifthis back-pressure is not powerful enough to overcome the frictionalpressure between the nut D and jaws E E, then the nut still remainsstationary and feeds the drill-rod forwardly at full speed. As soon,however, as the back-pressu re is strong enough to overcome suchfrictional pressure between the nut and jaws the nut revolves with thedrill-rod and automatically varies the feed of the drill-r0d. The degreeof variation in the feed of the drill depends upon the speed of rotationof the nut D, and the speed of rotation of nut depends upon theback-pressure or the resistance the auger meets with. Thus the harderthe material in which the auger is IIO worked the greater theback-pressure, the faster the speed of rotation of the nut D, and theslower the feed of the drilLrod. On the other hand, the softerthematerhl the less the back-pressure and the slower the speed of rotationof the nut and faster the drill-rod is fed forwardly.

As the variation in the feed of the drill-rod, as above described, isdue entirely-to the variation of the back-pressure on the rod, itfollows that as the back-pressure varies as the auger penetrates orbores through materials of dilferent degrees of hardness the variationsin the feed of the drill-rod are automatically effected. Only one andthe same drill-rod and feeding mechanism, therefore, is required foruse, and all danger of injury to the anger or drill, due to too rapidfeedingof the drill-rod as the auger suddenly passes from a soft to ahard material, is avoided.

In Figs. 15 and 16 I have shown a modified form of feed mechanism forthe drill-rod 0, wherein the sections of the nut D are hinged to etherand pivoted to a disk R, which finds 9 its bearing on the top of thescrew-threads on rod 0, being loose thereon, and said nut-sections havean adjusting-screw r for engaging them with and disengaging them fromthe drill-rod O. The disk or wheel R is in frictional engagement withone or more like disks S S, rotating with the armature-shaft g,bein9keyed thereon, so as to have a movement along the shaft 9 when adjustedby means of a right and left screw-bolt r to vary the frictional contactbetween disks S and disk R. In this case, as shown, the threads on thedrill-rod are of a reverse pitch to that for the threads .shown in Fig.1, or are left-handed to avoid interposing idler-disks between the disksS and R. In this construction the disk R and nut D are continuouslyrevolved by the armature-shaft, or the nutis always in motion, and thefaster the nut revolves the greater the feed of the drill-rod. As thebackpressure on the drill-rod falls on the disk It, such pressureopposes the frictional pressure between the disk It and disks S S on thearmature-shaft to effect a variation in the speed of rotation of nutDand consequent variation in the feed of rod 0. To withdraw the rod 0from the nut D, the screw '1" thereon is adjusted to spread thenut-sections apart until their threads disengage from those on thedrill-rod.

As it is obvious that the novel constructions and arrangements of partsmay be greatly varied without departing from the spirit of my invention,I do not confine myselfv to the same, as shown and described. Thus, forinstance, while I have illustrated a preferable form of feed mechanismfor the drill-rod it is obvious that any other suitable or the wellknownhand or other feeds can be substituted.

From the foregoing it will be noted that as all the parts of theelectric motor, as well as the electrical resistance-box, switch, andtheir circuit-connections, areinclosed in the casing A said parts arepreserved from injury by careless handling of the 'drill or by fallingrock or debris. Dust and dirt are excluded from the working parts of themotor and from the terminals of the switch, so that they are alwaysbright or clean to obtain perfect contact when necessary changes ofcircuit are made for controlling the operations of the motor and in turnthose of the drill-rod. Furthermore, as the casing A is closed theoperators or attendants cannot inadvertently catch hold of any livewires or other current-conducting parts in said casing, and, lastly,access of fire-damp or explosive gases to the sparks at thecommutator-brushes or switchterminals, and consequent explosion of sameby said sparks when the drill is used in mines, is prevented, andgreater safety of working electrically-actuated drills is obtained. Asthe casing A has the removable cap a with part of the electrical devicessecured thereto, all of said parts are easy of access for making quickrepairs and replacement. As all the electrical devices are secured tothe bed-plate a, as is also the drill-rod O, and as the sectionalfeeding-nut D is applied directly to the drill-rod, the number of partsare very much diminished and the drill is lighter and more compact, sothat it can be easily and quickly handled in shafts of mines or otherconfined places. As the sectional nut D is loose on the drill-rod andhas an adjusting clamping device which does not impose any friction onthe drill-rod, the full power of the motor is used for drilling and isnot wasted in overcoming needless friction,and, further, as said nut isin sections it can be readily separated to disengage its sections fromthe drill-rod, so that it can quickly be pulled back out of the drilledopening. These described advantages, in conjunction with the minoradvantages hereinbefore set forth, afford a portable drill of extremeusefulness and durability, as it can easily and quickly be handled underall conditions of service. and its parts are correspondingly repaired orreplaced, and great safety in working or operating it is assured.

What I claim is 1. The combination of a rotating andlongitudinally-feeding drill-rod, as'upport there for, an electric motorhavingarotating armature-shaft on said support, gearing betwe saidarmature shaft and drill-rod, feeding mechanism for the'drill-rod, anddevices for disengaging said feeding mechanism from the drill-rod toadmit of a quick return of the drill-rod independently of said feedingmechanism, substantially as set forth.

2. The combination of a rotating and 1ongitudinallyfeeding drill-rod, asupport therefor, an electric motor having a rotating armature-shaft onsaid support, gearing between said armature-shaft and drill-rod, anelectric switch, resistance-box, and circuit-connections for theelectric motor, substantially as set forth.

3. The combination, with a rotating and IOO ITO

longitudinallyfeeding drill-rod, a support] therefor, an electric motorhaving a rotating armaturesl'iaft and the field-magnets of the motorforming a part of said support, gearing between said armature-shaft andthe drill rod, feeding mechanism for the drill-rod, de-

vices for disengaging said feeding mechan= ism from the drill-rod toadmit of a quick returnof the drill-rod ii'idependently of said feedingmechanism, and a casing for said motor, substantially as set forth.

4. In combination with a support or column I the casing A, an electricmotor, electrlcal switch, resistance-box, and circuit-eonneetionstherefor, all supported on and located within said casing, a rotatingdrill-rod O, mounted on said casing and in gear with the motor, andfeeding mechanism for the feed-rod, substantially as set forth.

5. In combination with a column or support P, a base-plate a, swiveledto said support and composed of sections, each section having aneleetro-niagnet secured thereto, a casing on said bed-plate, an armatureforsaid magnets, an armature-shaft suitably mounted in said casing, adrill-rod supported on the bed-plate, and gear connection between thedrill-rod and the armature'shaft, substantially as set forth.

0 (i. The combination of bed-plate a, ends a w, secured thereto, cap a",connecting said ends and bed-plate and forminga closed casing A,electromotor F within said casing A, and a drill-rod C, supported onsaid bed-plate and having gear connections with said motor,substantially as set forth.

7. The combination of bed-plate (I, ends a a metal cap a openings ii inend a doors or covers for said ends and forming a casing A, electricmotor F within said casing A,a drill-rod C, and gear connection betweensaid motor and rod, substantially as set forth.

8. In combination with a drill-rod support, a closed casing A, made insections, one of which is removable from the other, an electric motorwithin said casing, an electric switch, one part of which is secured tothe fixed casing-section and the other part to the removableeasing-section, substantially as set forth.

9. In combination with drill-rod C, a support therefor, electric motor Fin gear with said drill-rod, resistance-box L, switch K,circuit-connections for said motor, switch, and resistance-box, and aclosed casing A for said motor, switch, and resistance-box,substantially as set forth.

10. In combination with the base-plate at, having ends a a drill-rod 0,metal cap (t having secured theretoa resistance-box, part of an electricswitch, and a coupling-section for the ends of the line-wire, the otherpart of said switch being connected to one of the ends a a an electricmotor within said cap and ends, and a drill'rod O in gear with saidmotor, substantially as set forth.

11. In combination with the sectional bedplate (1, having sectionalsleeve l3, drill-rod C in said sleeve, field-magnets f, secured to saidbed-plate sections, ends a a secured to said plate, an armature mountedin said ends, drill-rod C, and gearing between the rod andarmature-shaft, substantially as set forth.

1?. In combination with bed-plate a, drill red C, ends a a secured tosaid bed-plate, an electric motor the field-magnet poles of which haveend horns or lugs f connected to ends a (t cap a and gearing betweensaid feed-rod and motor, substantially as set forth.

13. In combination with a drill-rod C, an electric motor in gear withsaid rod, a switchbar K, having ratchet-wheel Z, a spring-pawl Zengaging with said ratchet-wheel, resistance-box L,eircuit-coiniections, and a closed casingri, substantially as set forth.

14c. The combination of a rotating and longitudinally-feeding drill-rodhaving exterior screw-threads, a sectional threaded nut on saiddrill-rod, and adjustable jaws for supporting said sectional nut forengaging the latter with the drill-rod, and for imposing an adjustablefriction or clamping contact between the sectional nut and the jaws,substantially as set forth.

15. The combination of a rotating and longitudinally-feedingscrew-threaded drill-rod, a sectional SG1GW1llll) on said rod, frictionde vices for said nut, which act to hold the sectional nut stationary tofeed the drill-rod when there is no back-pressure on it, and whichpermit the nut to rotate to vary the feed of the drill-rod when subjectto backpressure, substantially as set forth.

16. The combination of a rotating andlongitudiually-feedingdrill-rodexteriorlythreaded, a sectional nut onthe drill-rod, adjustable jaws for supporting said nut, andspring-actuated devices between the nut-sections for spreading themapart out of engagement with the threads on the drill-rod when theadjustable jaws are moved apart, substantially as set forth.

17. In a rock-drill, the combination of a 1'0- tating andlongitudinally-feeding drill-rod O, the sectional feedingnut D, looseupon and engaging with said rod, and adjustable clamping devices forsaid nut to hold it in a fixed position and admit of said nut rotatingwith the red C to vary its feed, substantially as set forth.

18. In a rocledrill, the combination, with a rotating andlongitudinally-feeding red C, the sectional nut D, loose on said red C,clamping and supporting jaws E E, and adjusting devices for moving saidjaws to impart a clamping-friction between the jaws and nut withoutcreating friction or clamping contact between the nut and drill-rod,substantially as set forth.

19. In combination with bed-plate a, the rotating andlongitudinally-sliding drill-rod G, sliding jaws E E, having adjustingmechanism, and sectional nut D, interposed between the jaws and rod,which nutis stationary for feeding'the red at a given feed and rotateswith the rod to vary said feed, subsantially as set forth.

20. In a rock-drill, the combination of the drill-rod C, the sectionalnut D, springs in-' terposed between the meeting edges of thenut-sections, movable jaws E E for supporting said nut-sections on rod0, and adjusting mechanism for said jaws, substantially as set forth.

21. In a rock-drill, the combination of a motor-shaft, a feedingdrill-rod separate from and driven by the motor-shaft, a feeding devicefor the drill-rod, a clamp for said feeding device to hold the latterstationary to feed the drill when there is no back-pressure on it topermit the feeding device to rotate for varying the feed of thedrill-rod when sub-

